The purpose of this study was to investigate the effects of dietary chungguajang powder on blood glucose level and hepatic activities of antioxidant enzymes in normal and streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male ratt ($200{sim}220g$) of six groups including normal group fed normal diet (N), diabetic group fed normal diet (C), diabetic groups fed chunggugjang powder diet (DC-1%, DC-5%, DC-10%, DC-20%) were used for the experiments. Diabetes was induced by single intraperitoneal injection of streptozotocin as a dose of 70 mg/kg body weight. After 3 weeks the animals were sacrificed and hepatic activities of antioxidant enzymes, serum level of glucose and organ weight were evaluated. Food and water intakes were higher in diabetic groups than normal group. Body weight gain and food efficiency ratio were lower in diabetic groups. However, they were higher in chunggugjang diet groups (DC) than normal diet group (C). The serum glucose levels were significantly lower (p<0.05) in the diabetic groups fed chunggugjang diet (DC-10%, DC-20%) than diabetic group fed normal diet (C). Hepatic activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione S-transferase were lower in diabetic groups than normal group and they were significantly lower in diabetic groups fed chunggugjang diet (DC-20%) compared to diabetic rats fed normal diet (p<0.05). In conclusion, these results indicated that chunggugjang powder would have antidiabetic and antioxidant effects in STZ-induced diabetic rats.